Circular Servo Motors can control speed with very accurate position accuracy and can convert voltage signals into torque and speed to drive the control object. Servo motor rotor speed is controlled by the input signal and can respond quickly, used as an executive element in automatic control systems, and has the characteristics of small electromechanical time constant and high linearity, which can convert the electrical signal received into the angular displacement or angular velocity output on the motor shaft. It is divided into two categories: DC and AC servo motors, whose main characteristics are that there is no self rotation when the signal voltage is zero, and the speed decreases uniformly with the increase of torque.